It was found that tritiated inositol injected into rat and mouse sciatic nerve is rapidly incorporated into phosphatidylinositol. The major sites of this incorporation, presumably sites of phosphatidylinositol synthesis, were found to be within the axon as determined by EM autoradiographic techniques. These studies have been extended. Tritiated ethanolamine was used as a precursor to study phosphatidylethanolamine synthesis in mouse sciatic nerve. Sites of incorporation were localized mainly to Schwann cell cytoplasm, and not to axoplasm. Biochemical studies were initiated to characterize the enzyme activities associated with phosphatidylinositol metabolism in peripheral nerve. Under optimal conditions for each enzyme, CDP-diglyceride-dependent inositol transferase was found to be 200 times more active than choline phosphotransferase. Both enzymes were found to accumulate in 5mm segments of nerve proximal to a ligature, suggesting that both enzymes are supplied to the axonal processes from the nerve cell body. Experiments are in progress to determine whether inositide metabolism is altered in diabetic animals.